Splittable composite filament



D, 24,1968 D. TANNER 3,418,200

SPLIT'I'ABLE COMPOSITE FILAIBNT Filed Nov. 27, 1964 6 v INVENTOR United States Patent 3,418,200 SPLIITABLE COMPOSITE FILAMENT David Tanner, Salisbury, Md., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Nov. 27, 1964, Ser. No. 414,225 Claims. (Cl. 161--177) ABSTRACT OF THE DISCLOSURE A composite filament with core and minute lobe components of different synthetic polymers. The lobes are disposed about the core and, due to the difference in compositions, readily separable when the filament or a fabric is subjected to mechanical agitation in boiling water.

This invention relates to improved synthetic polymer filaments and more particularly to improved composite filaments produced from synthetic polymers.

In recent years, the introduction of synthetic yarns, such as those made from polyamides and polyesters, has led to fabrics having high strength, improved durability and, most important, improved launderability and wrinkle resistance. However, fabrics made from these yarns, particularly, the continuous-filament yarns, are imperfect and can be improved in a number of respects. For example, fabrics of filamentary polyamide yarns tend to have a slick, cold hand and are deficient in cover and luster in many uses. Thus, in spite of their outstanding functional properties, fabrics produced from these yarns do not have all of the properties and the aesthetic qualities desired in an ideal fabric.

An object of this invention is to provide an improved composite filament which may be used to produce yarns and fabrics of greatly enhanced aesthetic appeal and improved properties. Another object is to provide composite filaments which split into three or more independent filaments upon suitable treatment in fabric form. A further object is to provide composite filaments which afford, after splitting, several components with very low deniers, which are not obtainable by conventional melt-spinning operations. Other objects will become apparent from the discussion hereinafter.

The objects of this invention are accomplished by a composite filament which comprises, in general, a longitudinally extending core component of a first synthetic polymeric composition and a plurality of longitudinally extending lobe components adhered to the core component, the lobe components being of a second synthetic polymeric composition. The core component has both greater denier and, preferably, higher shrinkage characteristics than the lobe components. Each part which consists of the second synthetic polymeric composition is readily separable from the remainder of the composite filament. The terminology readily separable is meant to define the tendency of the lobe components consisting of a second synthetic polymeric composition to separate from the remainder of the composite filament to form separate and independent filaments under such predetermined conditions as vigorous mechanical agitation while the composite filament is immersed in boiling water.

The number and shape of lobe components on the core component can be varied widely depending upon the effect desired. Based upon an optimum compromise between the aesthetics and the practical production of the filaments, it is preferred that there be three to eight lobe components, four to six lobes being especially preferred. It is also preferred to have the lobe components symmetrically placed about the core component and to have each lobe component of substantially identical denier.

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The embodiments of this invention and their advantages can be more readily understood by referring to the accompanying drawings.

FIGURE 1 is an axial cross-sectional view of a spinneret assembly used in preparing the composite filaments of this invention;

FIGURES 2 and 3 are greatly magnified views of spinneret orifices useful in preparing the composite filaments of this invention;

FIGURE 4 is a greatly magnified cross-sectional view of a tetralobal composite filament of this invention;

FIGURE 5 is a greatly magnified cross-sectional view of a hexalobal composite filament of this invention; and

FIGURE 6 is a greatly magnified cross-sectional view of a tetralobal composite filament wherein only the lobe tips are readily separable components.

The filaments of this invention are prepared by extruding at least two different polymers through a spinneret assembly of the type shown in FIGURE 1. Referring to FIGURE 1, front or bottom plate 1 with orifices 2 is recessed at the back about plateau-like protrusions 4. Each orifice consists of capillary 21 at the exit (which, in the present case, is of a non-round shape, such as a cruciform as shown in FIGURE 2) and larger counterbore 22 leading to the capillary from the plateau. Back or top plate 7 is sealed against and spaced from the front plate by gasket 6 and shim 16, the former being ring-shaped and located near the periphery of the opposing faces of the two plates and the latter being disc-shaped and located concentric with the two plates. Relatively unconstricted region 12 between the two plates is interrupted at intervals by constricted regions 15 between the opposing face of the back plate and plateaus 5 of the protrusions from the front plate. The back plate is partitioned on top by outer wall 19 and inner wall 29 into annular chamber 8 and central chamber 9. The annular chamber communicates with the constricted regions between the two plates through counterbored apertures 10, consisting of terminal capillary 23 and counterbore 24, and the central chamber communicates with the intervening relatively unconstricted region through holes 11. The two plates are retained in place by cap 18 threaded onto the end of the back plate. The upper part of the housing (not shown) receives suitable piping or other supply means for separate connection to the two chambers, which may constitute distribution or filtering spaces as desired. Pin 14 through cylindrical openings (opening 25 in the front plate and opening 26 in the back plate) near one edge of the plates insures the desired alignment of the two plates.

FIGURES 2 and 3 represent cross-sectional views of spinneret orifices which can be utilized to form the composite filaments of this invention. In FIGURE 2, the cruciform orifice consists of core portion and four arms 42, the lobe components being formed by the polymer passing through the arms. FIGURE 3 illustrates an orifice which can be utilized to form hexalobal composite filaments and consists of a core portion and six triangular shaped arms 52.

FIGURES 4 through 6 illustrate cross-sectional views of embodiments of composite filaments of this invention. FIGURE 4 shows a tetralobal filament which consists of an axial core component surrounded by four lobe components 62 whereas FIGURE 5 demonstrates a hexalobal filament having an axial core component surrounded by six lobe components 72. FIGURE 6 illustrates the embodiment wherein the core component has lobe portions 82 which are of the same synthetic polymer. The lobe components 84 at the tips of the lobes consist of a different synthetic polymer and are readily separable under predetermined conditions.

Operation of the described apparatus in the practice of this invention is readily understood. Separate polymers are supplied to the inner and the outer chambers, respectively, of the back plate; the former flows through the openings into the relatively unconstricted space 12 between back and front plates, through the relatively constricted regions between the plateaus and the opposingplate face, and through the extrusion orifices to form the lobes of a filament while the latter passes first through the apertures in the back plate and directly into and through the aligned orifices in the front plate to form the core.

The flow rates of the synthetic polymer compositions which form the core component and lobe components can, of course, be varied to effect the desired denier in the filaments after separation. It is preferred that the denier of the core component be at least twice the denier of the individual lobe components and may conveniently be up to about times the denier of the lobe components.

With respect to the components, it is preferred to maintain a core denier of at least 1, preferably from about 1 to about 4, and the denier of the lobes from about 0.05 to about 0.5. These ranges will achieve the optimum aesthetic affects.

It is also preferred to have the synthetic polymeric composition which comprises the core component to have the higher relative shrinkage characteristics under the conditions of fabric finishing which prevail. This will, of course, result in the smaller denier lobe component filaments being brought to the surface of the fabric. As disclosed in US. Patent 3,117,906, the yarn history, such as the initial polymers used, spinning and drawing conditions, determine the relative amounts of shrinkage be tween the filament components. These conditions may be varied in a suitable manner to achieve the desired fabric properties.

The following examples are illustrative of the invention but not in limitation thereof. All parts and percentages are by weight unless otherwise indicated. The expression relative viscosity as used herein refers to the ratio of the flow time in a viscometer of a polymer solution relative to the flow time of the solvent by itself. Measurements of relative viscosities given in the exam pics are made with the following solutions:

5.5 grams of polyamide in ml. of 90% formic acid at 25 C., or

2.15 grams of polyester in 20 ml. of a 7/10 mixture of trichlorophenol/ phenol at 25 C.

Example I Polyhexamethylene adipamide, having a relative viscosity of 40, and polyethylene terephthalate, having a relative viscosity of 20, are prepared in the conventional manner. The polymers are melted separately and the respective melts led to a spinneret assembly of the type shown in FIGURE 1 where 34 filaments are extruded through cruciform orifices (FIGURES 2), one of the polymers being fed to the center of the cruciform to form a core and the other polymer bein fed to the tips of the cruciform to form lobes on the filament. The filament bundle is quenched and wound up in the conventional manner. The yarn is then drawn on the drawtwister at 312 (286 m./min.) y.p.m. over a 95 C. pin and a 180 C. plate, the draw ratio being in the range of 2.6 to 2.8. When the yarn is removed from the package, it does not crimp as does similar yarn spun with the two polymers in side-by-side relation.

When transverse cross-sections of the yarn are examined microscopically, the filament is found to consist of a core of one polymer surrounded by four symmetrically spaced lobes of the other polymer as illustrated in FIG- URE 4.

As a test, part of the yarn formed is immersed in boiling water and subjected to vigorous mechanical agitation. The result is that the four lobes split away from the core and from each other to form five independent filaments. Table I below shows the polymers used in the lobes and core respectively, gives the weight ratios of polymers employed and the denier of the core and of the individual lobes.

The remaining portion of the yarns prepared (but not tested above) is sized and woven into taffeta and twill fabrics of 2.0 to 2.5 oz. per sq. yd. (68 to g./m. scoured under relatively relaxed conditions and heat set according to normal fabric finishing conditions which are set forth in Example I of US. Patent 3,117,906. Crosssections of yarn are removed from the finished fabrics and show that each filament has split into five parts as a result of the scouring operation. The fabrics have unusual warmth and softness, high bulk and covering power, and silk-like appearance suitable especially for blouses and lingerie garments. Subjecting the fabrics to brushing, napping, and calendering creates a fine surface fuzz leading to even higher bulk, cover and softness.

TABLE 1 Polymer Ratio, Polyamide/Polyester Core Lobe Component Lobe Denier o 0.125 Polyamide 0.25 do 0.125

Polymer Denier Polymer Polyester Example II Yarn is prepared as in Example 1 except that the polyester has a relative viscosity of 25 and 2.5% by weight of the antistatic agent of Example III is added. In extrusion, the fiow rates of the two polymers are adjusted so that the core and part of each lobe consists of polyethylene terephthalate and the tips of the lobes consist of polyhexamethylene adipamide as illustrated in FIGURE 6. When fabrics are prepared and finished, as in Example I, the polyhexamethylene adipamide lobes split off to give five independent filaments. The polyethylene terephthalate core provides a Z-denier filament and the lobe tips provide four 0.25 denier filaments. Fabrics prepared from this yarn have a soft silk-like appearance and also have improved antistatic properties due to the inclusion of the antistatic agent.

Example III Polyhexamethylene adipamide, having a relative viscosity of 41.8, and polyethylene terephthalate, having a relative viscosity of 26, are prepared in the conventional manner except that the olyhexamethylene adipamide contains dispersed therein 2.5 by weight of an antistatic agent having the following formula:

wherein n is in the range of 30 to 40.

The polymers are melted separately and extruded as in Example I except that the spinneret orifices are as illustrated in FIGURE 3. The polyethylene terephthalate is fed to the center as in Example I to form the core while the polyhexamethylene adipamide is fed to the arms of the spinneret orifices to form six lobes which surround the core as illustrated in FIGURE 5. The yarn is quenched and wound into a package in the conventional manner and then drawn on a draw-twister at a ratio of 3.4 as in Example I. When the yarn is immersed in boiling Water and subjected to vigorous mechanical agitation, the six lobes separate from the core and from one another to form seven filaments, the filament formed from the core having a denier of about 1.8 and those formed from the lobes having a denier of about 0.25 each.

When the yarn is woven into fabrics and the fabrics finished as described in Example I, the fabrics are similar to those of Example I but are slightly superior in bulk and softness.

Example IV Polyhexamethylene adipamide containing 2.5% of the antistatic agent of Example III is melt blended with hexamethylene isophthalamide to form a melt blend containing by weight of the isophthalamide. Yarns are prepared following a procedure of Example I to produce filaments having a core of 2 denier polyethylene terephthalate and 4 small lobes consisting of the above melt blend, the lobes being 0.1 denier each. When fabrics are prepared and finished as described in Example I these lobes split off to form four 0.1 denier filaments and one 2 denier filament of polyethylene terephthalate. The fabrics are similar to those of the Example I except that they have higher :bulk due to high differential shrinkage between the components.

Example V A polymer is prepared in an autoclave from a 50% aqueous solution of the salt of bis-(para-aminocyclohexyl) methane and azelaic acid. The diamine consists of 70% transtrans, cis-trans and about 5% cis-cis isomers. As a viscosity stabilizer, 17.5 millimols of acetic acid are added for every mole of the polyamide salt. The salt solution is heated under 50 lbs. per square inch (3.5 kg./cm. pressure for 2 hours while the temperature is raised to 285 C. The pressure is then reduced to atmospheric while the temperature is raised to 315 C. and the polymer held under these conditions for one hour. It is then extruded and cut to flake. The polymer has an inherent viscosity of 0.82 as measured on a solu tion containing 0.5 gram polymer in 100 ml. of m-cresol. The yarn is prepared following the procedure of Example I using the polyamide as the core and polyethylene terephthalate as the lobes of each filament. The yarn is drawn on a draw winder over a 120 C. pin and then steam relaxed 9% following the procedure of U.S. Patent 3,003,222. When fabrics are prepared from this yarn as in Example I, the polyethylene terephthalate lobes split off to form 0.4 denier filaments leaving the core as a 1.7 denier filament. The fabrics have soft, silky aesthetics and are crisper and have higher recovery than the fabrics of Example I because of the higher recovery polyamide component.

Example VI The yarn is prepared following the procedure of EX- ample I, the relative amounts of the two polymers being selected so that the filaments are splittable to a 1.7 denier polyethylene terephthalate filament from the core and four 0.4 denier polyhexamethylene adipamide filaments from the four lobes. The yarn is woven into a taffeta fabric which is soaked in 1% ammonium chloride solution at room temperature for 16 hours. The fabric is then air dried, heated at 150 C. for five minutes and then treated with formaldehyde gas at this temperature for 15 minutes. The fabric is then scoured under rel-axed conditions and heat-set as described in Example I.

The fabric is more resilient than non-cross-linked fabric and is superior to a cross-linked all-polyamide fabric in that the fabric may be creased and shaped while the allpolyamide fabric cannot. In comparison with fabric prepared from a side-by-side two component yarn consisting of polyethylene terephthalate on one side of the filament and polyhexamethylene adipamide on the other, this fabric is superior in softness and general aesthetics.

The foregoing examples illustrate the advantage of the novel composite filaments of this invention in the production of fabrics of greatly improved aesthetics. Moreover, the novel composite filaments of this invention have advantages in processing because a single relatively high denier straight filament is produced for weaving into the fabric but in the final fabric form a large number of very fine filaments are present to give the desired aesthetics. In addition, the filaments produced by splitting may have differential shrinkages to give a desirable bulking effect in the fabric.

Suitable polymers for use as one of the components of this invention can be found in various groups of synthetic fiber-forming materials. Since it is desired to separate the filaments into their component sections by mechanical action, the components should have relatively low adhesion to each other. Because of their commercial availability, ease of processing, and excellent properties, the condensation polymers and copolymers, e.g., polyamides, polysulfonamides, and polyesters and particularly those that can be readily melt-spun are preferred for application in this invention. Suitable polymers can be found, for instance, among the fiber-forming polyamides and polyesters which are described in such patents as U.S. Patents 2,071,250, 2,071,253, 2,130,523, 2,130,948, 2,190,770, and 2,465,319. The preferred group of polyamides comprises polyhexamethylene adipamide, polyhexamethylene sebacamide, polyepsiloncaproamide, polyamides from bis (tp-aminocyclohexyl)methane and dicarboxylic acids containing 6 to 14 carbon atoms, particularly dodecanedioic acid, and the copolymers thereof. Suitable polyesters, besides polyethylene terephthalate, are the corresponding copolymers containing sebacic acid, adipic acid, isophthalic acid, as well as the polyesters containing recurring units derived from glycols with more than two carbons in the chain, e.g., diethylene glycol, butylene glycol, decamethylene glycol, and trans-bis-l,4-(hydroxymethyl)-cyclohexane.

Other groups of polymers useful as components in the filaments of the present invention can be found among the polyurethanes, the polyureas, cellulose esters, and cellulose ethers as well as among the polyhydrocarbons such as polyethylene or polypropylene and the polyvinyl compounds such as polyacrylonitrile, polyvinylchloride, polyvinylidene chloride, polyvinyl alcohol, and copolymers containing the monomers of these polymers and similar polymers as disclosed in U.S. Patents 2,601,256, 2,527,300, 2,256,360, and 2,436,926.

The yarns of this invention preferably contain a durable antistatic agent. The antistatic agent should be present in a concentration of at least 2% by weight of the filament with about 4% being a convenient upper limit. The antistatic agent may be added to either or both of the polymeric compositions used in producing these yarns. Suitable antistatic agents include the high molecular weight poly(alkylene ethers), i.e., those in the molecular weight range of 1300 to 200,000.

The poly(alkylene ethers) which may be employed are either ethylene oxide, propylene oxide or ethylene oxidepropylene oxide condensation products, i.e., the products contain from two to three carbon atoms in the alkylene group with two of the carbon aoms being intralinear carbon atoms connecting intralinear ether-oxygen atoms. Preferably, the poly(alkylene ether) is an ethylene oxide polymer which may be terminated or capped by hydroxyl groups or by one or more ether end-groups of the formula OR, where R is an alkyl, aryl, or aralkyl group, such as methyl, ethyl, isooctyl, decyl, lauryl, tridecyl, nonylphenyl, dodecylphenyl, phenyl, naphthyl and the like. Residues of coupling compounds or chain-initiating agents, such as bis-phenol, may be present. Indeed, when the specified number of ethylene oxide units are present, copolymer constituents in addition to those mentioned may be included in the polymer chain. Other elements or radicals may be introduced into the R groups provided they are not reactive with the hydrophobic polymer, e.g., halogen, especially fluorine, a phosphite or phosphate to decrease fiammability, and hypophosphite or phosphinate to improve light durability.

Although the filaments of this invention have been produced in the examples by the melt-spinning technique, it should be obvious that other spinning methods such as plasticized melt-spinning, dry spinning or wet spinning can be employed successfully.

What is claimed is:

1. A splittable composite filament which comprises a longitudinally extending core component of a first synthetic polymeric composition and from three to eight longitudinally extending peripherally spaced lobe components adhered to said core component, said lobe components being of a second synthetic polymeric composition, said core component having a denier of from about 1 to about 4, said lobe components each having a denier of from about 0.05 to about 0.5 and being readily separable from the remainder of the composite filament, said compositions being incompatible as evidenced by a relatively low level of adhesion between the core and lobe components.

2. The composite filament of claim 1 wherein said lobe components are symmetrically disposed relatively and with respect to the core component.

3. The composite filament of claim 1 wherein one of said compositions is a polyamide and the other is a polyester.

4. The composite filament of claim 1 wherein one of said compositions consists essentially of polyhexamethylene adipamide and the other consists essentially of polyethylene terephthalate.

5. A splittable composite filament which comprises a longitudinally extending core component of a first synthetic polymeric composition and a plurality of longitudinally extending lobe components adhered to and substantially symmetrically disposed on said core component, said lobe components being of a second synthetic polymeric composition, said core and lobe components containing at least 2%, by weight, of an antistatic agent consisting of a poly(alkylene ether) with a molecular weight of from 1,300 to 200,000, said core component having a denier of from about 1 to about 4, said lobe components each having a denier of from about 0.05 to about 0.5, being substantially equal in denier and being readily separable from the remainder of the composite filament, said compositions being incompatible as evidenced by a relatively low level of adhesion between the core and lobe components.

References Cited UNITED STATES PATENTS 2,945,739 7/1960 Lehmicke 264-177 2,987,797 6/1961 Breen 161-177 3,117,906 1/1964 Tanner 161-406 2,531,234 11/1950 Seckel 161-142 3,017,686 1/1962 Breen et al 161-177 FOREIGN PATENTS 963,320 7/1964 Great Britain.

ROBERT F. BURNETT, Primary Examiner.

R. L. MAY, Assistant Examiner.

US. Cl. X.R. 264-171, 177 

